The present invention relates to an operational amplifier circuit, a driving circuit and a driving method.
Conventionally, as a liquid crystal panel (electro-optical device) which is used for an electronic instrument such as a portable telephone, there have been known a passive matrix type liquid crystal panel and an active matrix type liquid crystal panel which uses switching elements such as thin film transistors (abbreviated as TFT hereinafter).
Although the passive matrix type is advantageous compared to the active matrix type in that the lowering of power consumption can be easily obtained, the passive matrix type has a disadvantage that the multi-colorization and the moving picture display are difficult. With respect to a technique for lowering the power consumption in the passive matrix type, there has been known a conventional technique disclosed in Japanese Laid-open Patent Publication 7-98577, for example.
On the other hand, although the active matrix type has an advantage that this type is suitable for the multi-colorization and the moving picture display, the active matrix type has a disadvantage that the lowering of the power consumption is difficult.
Recently, in the field of the portable type electronic instrument such as a portable telephone set, the demand for multi-colorization and moving picture display has been increasing to provide high quality images. Accordingly, in place of the passive matrix type liquid crystal panel which has been used heretofore, the active matrix type liquid crystal panel is now popularly used.
However, with respect to the active matrix type liquid crystal panel used for the portable type electronic instrument, to cope with the demand for the alternating current driving of the liquid crystal and the lowering of voltage of power sources, a voltage level of counter electrodes (common electrodes) which face pixel electrodes is inverted every scanning period, for example. Accordingly, due to the large charging/discharging of a liquid crystal panel and an operation current of an operational amplifier circuit which drives an analogue voltage, there has been a problem that the realization of the lowering of power consumption is hardly achieved.